Investigation of a methane flare during the excavation of the Silvan irrigation tunnel,Turkey

Bulletin of Engineering Geology and the Environment - Mechanized methods are being increasingly used in tunnel excavations to such an extent that to ensure safe construction and the economic...     

Estimating the energy production of the wind turbine using artificial neural network

Due to fluctuating weather conditions, estimating wind energy potential is still a significant problem. Artificial neural networks (ANNs) have been commonly used in short-term and just-in-time modeling of wind power generation systems based on main weather parameters such as wind speed, temperature, and humidity. Two different datasets called hourly main weather data (MWD) and daily sub-data (DSD) are used to estimate a wind turbine power generation in this study. MWD are based on historically observed wind speed, wind direction, air temperature, and pressure parameters. Besides, DSD created with statistical terms of MWD consist of maximum, minimum, mean, standard deviation, skewness, and kurtosis values. The main purpose of this study in particular was to develop a multilinear model representing the relationship between the DSD with the calculated minimum (P _min) and maximum (P _max) power generation values as well as the total power generation (P _sum) produced in a day by a wind turbine based on the MWD. While simulation values of the turbine, P _min, P _max, and P _sum, were used as the separately dependent parameters, DSD were determined as independent parameters in the estimation models. Stepwise regression was used to determine efficient independent parameters on the dependent parameters and to remove the inefficient parameters in the exploratory phase of study. These efficient parameters and simulated power generation values were used for training and testing the developed ANN models. Accuracy test results show that interoperability framework models based on stepwise regression and the neural network models are more accurate and more reliable than a linear approach.     

Design of the polyacrylonitrile-reduced graphene oxide nanocomposite-based non-enzymatic electrochemical biosensor for glucose detection

With the advantages of developed electronic devices, various biosensor applications have become attractive issues with excellent electrochemical performances against biomarkers and molecules in biomedical applications. In this study, novel polyacrylonitrile (PAN)-reduced graphene oxide (rGO) nanocomposite-based non-enzymatic electrochemical biosensors were prepared to investigate the detection performance of the glucose. The PAN-rGO nanocomposite-based biosensor detected glucose with a high sensitivity and stability due to enhanced redox mechanism arising from rGO additive. PAN-rGO nanocomposite-based biosensor detected glucose in (0.75–12) mM with a high sensitivity of 49 µAmM^?1 cm^?2 (2.5 times higher than PAN-based sensor). Concentration–response graphs correlating the non-enzymatic electrochemical signal to glucose concentration revealed a low limit of detection (LOD) of 0.6 mM within 1-min voltammetric cycle. The selectivity results confirmed a significant preferential response of the proposed PAN-rGO nanocomposite-based biosensor for glucose against possible interfering compounds. The proposed PAN-rGO nanocomposite-based biosensor has a great potential to be used as a nanostructured platform for detection of glucose in phosphate-buffered saline (pH 7.4) solution with high sensitivity, selectivity, stability, reproducibility, and fast response properties.

     

Compliant universal joint with preformed flexible segments

Journal of Mechanical Science and Technology - This paper introduces an original, fully compliant universal joint design. Many mechanisms with different dimensions are investigated. The proposed...     

Hydrogen production from 2-propanol over Pt/Al2O3 and Ru/Al2O3 catalysts in supercritical water

One of the alternative energy sources to fossil fuels is the use of hydrogen as an energy carrier, which provides zero emission of pollutants and high-energy efficiency when used in fuel cells, hydrogen internal combustion engines (HICE) or hydrogen-blend gaseous fueled internal combustion engines (HBICE). The gasification of organics in supercritical water is a promising method for the direct production of hydrogen at high pressures, with very short reaction times. In this study, hydrogen production from 2-propanol over Pt/Al₂O₃ and Ru/Al₂O₃ catalysts was investigated in supercritical water. To investigate the influences on hydrogen production, the experiments were carried out in the temperature range of 400–550 °C and in the reaction time range of 10–30 s, under a pressure of 25 MPa. In addition, different 2-propanol concentrations and reaction pressures were tested in order to comprehend the effects on the gasification yield and hydrogen production. It was found that Pt/Al₂O₃ catalyst was much more selective and effective for hydrogen production when compared to Ru/Al₂O₃. During the catalytic gasification of a 0.5 M solution of 2-propanol, a hydrogen content up to 96 mol% for a gasification yield of 5 L/L feed was obtained.     

Synthesizing high α-phase Si3N4 powders containing sintering additives

Fine grain α-phase silicon nitride (Si₃N₄) ceramic powders were produced via carbothermic reduction of colloidal SiO₂, which contained pre-mixed additives of sintering aids primarily consisting of oxides such as MgO and Y₂O₃. The powders that were pre-mixed in the starting reactants were chosen based on the final powder composition and on type and amount of the secondary phases desired for sintering. After synthesizing, powder properties were examined using standard characterization techniques (XRD, SEM, BET, etc). This technique of ceramic synthesis has advantages in providing nitride-based ceramic powders, which contain secondary in situ phases that are distributed as sintering additives. Silicon nitride ceramic powders synthesized using this method might therefore be readily sintered because the homogeneously distributed sintering additives were present in the starting materials. In this work, the processing parameters are described in terms of the synthesis conditions.     

PVA:Nano-eggshell microcomposite as an energy storage material for supercapacitors

Journal of Materials Science: Materials in Electronics - The development and advantages of wearable flexible electronics have become attractive issues with excellent electrochemical performances in...     

Effect of basic pumice on morphologic properties of interfacial transition zone in load-bearing lightweight/semi-lightweight concretes

The objective of this research is to determine the effect of basic pumice on morphologic properties of interfacial transition zone in load-bearing lightweight/semi-lightweight concretes. In this respect, it has been researched how the chemical and physical structure and the volumetric ratio of basic pumice affected the following three morphologic properties of interfacial transition zone: compactness, width and physical adherence. In accordance with the stated purpose, 15 concrete serials with various properties were produced using basic pumice as aggregate and 670 images were taken from the samples collected from these serials via scanning electron microscope (SEM). Semi-analytical detections were performed based on non-generalizing numeric data obtained in conclusion of the determination of grain limits in these images and comments on visual analysis. In accordance with these detections, it has been concluded that the basic pumice has a high level of potential to contribute to the morphologic properties of interfacial transition zone.     

Investigating on possible use of Diyarbakir basalt waste in Stone Mastic Asphalt

Stone Mastic Asphalt (SMA) improved for road construction which has been utilized in Europe and America for 40 years is a rather new process in Turkey. SMA basically consists of 93–94% aggregate and mineral fillers, 6–7% bitumen and additives. Road and construction industry consume stone in large amounts. Stone used are obtained from nearby quarries and carried to the location where they are to be used, destroying the nature and causing large costs. The constantly increasing demand on quarries harms the general structure of the earth thus causing the emergence of large scale environmental problems. The use of basalt waste from stone processing plants as aggregates and mineral filler in SMA might help to meet this increasing demand thus solving environmental problems. In this study, primarily some important material properties of fine and coarse basalt waste, taken from basalt processing plants in Diyarbakir, such as sieve analysis, chemical analysis, specific gravity, water absorption, Los Angeles abrasion loss value, soundness of aggregate by Na₂SO₄, flakiness index and stripping strength were determined. Then by using this waste material, a SMA was designed according to Turkish Highway Technical Specifications. Marshall stability and flow tests have been carried out on designed SMA specimens. Test results indicate that properties of the basalt waste and the SMA produced were within the specified limits and that these waste materials can be used as aggregates and mineral filler in SMA.